The ground plane is disabled.  That is, I have the ground prop turned off on Visible, RayTracing, Casts Shadows, etc.  I also have ground shadows disabled.   And I turned on the "3-ball icon" for depth cueing.  

And the TIFFs alpha plane is still black/white w/ no gray.  I'm getting the fade-out on screen, but no fade in the TIFF's alpha channel.

Is there some other way I should be disabling the ground prop?

FYI, I'm running Poser 7.01.109 on a PC, and I'm examing the TIFF with Photoshop CS/2.